Quench cooling system and method for fixed bed reactor

Abstract

The invention relates to the technical field of chemical reactors, in particular to a quench cooling system and method for a fixed bed reactor, and the system comprises temperature sensor array units which are distributed on each bed layer of the reactor and are used for collecting temperature data in real time; the intelligent control unit is connected with the temperature sensor array unit, receives the temperature data and sends a control instruction based on a preset algorithm, the flow regulating valve group unit and the heat exchanger unit; the flow regulating valve group unit is arranged on a cold shock gas pipeline and is used for accurately regulating and controlling the flow and the flow direction of the cold shock gas according to an instruction of the intelligent control unit; and the heat exchanger unit is connected with the quench gas pipeline and the raw material pre-heater and is used for recovering the waste heat of the quench gas for heat reutilization. According to the invention, strict temperature threshold control effectively prevents catalyst deactivation and temperature runaway caused by too high temperature, prolongs the service life of the catalyst, reduces production loss caused by failure shutdown of the reactor, and improves continuity and stability of production.

Description

Technical Field

[0001] The invention relates to the technical field of chemical reactors, and in particular to a cold shock cooling system and method for a fixed bed reactor. Background Art

[0002] In chemical production, the temperature of the catalyst bed in the fixed bed reactor often rises rapidly due to the exothermic reaction. Traditional cooling methods have many disadvantages, such as slow response to temperature changes and poor control accuracy, which can easily lead to catalyst deactivation, reduced reaction efficiency and safety hazards caused by temperature runaway. In addition, problems such as energy waste and low raw material utilization have also seriously restricted the sustainable development of chemical production. Therefore, it is urgent to develop an efficient, intelligent and environmentally friendly cold shock cooling technology. Summary of the invention

[0003] In view of the above-mentioned shortcomings of the prior art, the present invention provides a cold shock cooling system and method for a fixed bed reactor, which can effectively solve the problems mentioned in the prior art.

[0004] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0005] The present invention provides a cold shock cooling system for a fixed bed reactor, characterized in that it comprises:

[0006] A temperature sensor array unit, used for collecting temperature data in real time;

[0007] An intelligent control unit, used for receiving temperature data and issuing control instructions to the flow regulating valve group unit and the heat exchanger unit based on a preset algorithm;

[0008] The preset algorithm steps include data acquisition and preprocessing, feature extraction and operating condition identification, temperature prediction model prediction, control strategy generation and instruction output, and adjusting the control strategy according to the reactor operating conditions and bed temperature change trends to predict temperature changes;

[0009] Data collection and preprocessing include collecting temperature data of each bed layer of the reactor, cold shock gas flow rate, pressure, methanol concentration, pressure in the reactor, and reactant concentration, and filtering the temperature data; feature extraction and operating condition identification are to calculate the temperature change rate, cold shock gas flow rate change rate, and pressure change rate in the reactor to form a feature vector, and identify the reactor operating condition through the support vector machine model; the temperature prediction model predicts the temperature by selecting the ARIMA model or LSTM model according to the operating condition; the control strategy generation and command output are based on the comparison of the predicted temperature with the preset temperature threshold, and the cold shock gas flow rate, component ratio, and the start of cooling measures;

[0010] The flow regulating valve group unit is used to control the flow and direction of the cold shock gas according to the instructions of the intelligent control unit;

[0011] The heat exchanger unit is used to recover the waste heat of the cold shock air for heat reuse.

[0012] Furthermore, the preset algorithm of the intelligent control unit adjusts the control strategy according to the reactor operating conditions and the bed temperature change trend, predicts the temperature change and generates control instructions.

[0013] Furthermore, the preset algorithm steps of the intelligent control unit include:

[0014] Data acquisition and preprocessing: Obtain temperature data of the first and second sections of the reactor and other beds from temperature sensors ,... , where t represents time, n represents the number of beds, and the cold shock gas flow rate is collected at the same time ,pressure , methanol concentration and the pressure inside the reactor , reactant concentration ;

[0015] Temperature data For filtering, the formula is:

[0016]

[0017] in, is the temperature data after filtering, m is the moving average window width;

[0018] Feature extraction and working condition identification: Calculate the temperature change rate based on the processed temperature data , the formula is:

[0019]

[0020] in, is the time interval, and the cold shock air flow rate change rate is calculated at the same time , pressure change rate in the reactor , the temperature change rate , cold shock air flow rate change rate , pressure change rate in the reactor ,pressure , methanol concentration and the pressure inside the reactor , reactant concentration Composition of feature vectors: ;

[0021] The characteristic vector is identified through the working condition classification model to judge the current reactor working condition. The reactor working condition includes stable working condition and fluctuating working condition. The working condition classification model adopts the support vector machine model, and the decision function is:

[0022]

[0023] Where w is the weight vector and b is the bias. When , it is determined to be a fluctuating condition; when When , it is judged as a stable working condition;

[0024] Temperature prediction model prediction: Different temperature prediction models are selected according to the working condition identification results. If it is in a stable working condition, the ARIMA model based on time series is used for temperature prediction; if it is in a fluctuating working condition, the prediction model based on long short-term memory network is used;

[0025] For the ARIMA model, the temperature time series is differentiated, and the differentiated series is assumed to be , the parameters of the ARIMA model are determined by the least squares method, including the autoregressive order p, the difference order d, the moving average order q and the model coefficient, and the model is used to predict the temperature value in the future , where k is the prediction step length, and the prediction formula is:

[0026]

[0027] in, and are the autoregressive and moving average coefficients, respectively. is a white noise sequence, is a constant;

[0028] For the LSTM model, historical temperature data and other related parameters are used as input sequences, and the future temperature forecast value is obtained through forward propagation calculation of the model. ,The training process of the LSTM model adjusts the network weights through the back-propagation algorithm to minimize the prediction error;

[0029] Control strategy generation and command output: Based on the predicted temperature value With preset temperature threshold , , For comparison, if the predicted temperature And there is an upward trend, generating a control command to increase the cold shock air flow, the control command is achieved by adjusting the opening of the flow control valve, the opening change Deviation from predicted temperature Proportional control strategy can be adopted, the formula is:

[0030]

[0031] in, is the proportionality coefficient. At the same time, according to the current methanol concentration According to the temperature changes, adjust the ratio of methanol to inert gas in the cold shock gas. If the temperature rises quickly and the methanol concentration is low, increase the methanol ratio; if the temperature rises slowly and the methanol concentration is high, increase the inert gas ratio;

[0032] If the predicted temperature In addition to increasing the cold shock air flow rate, start cooling measures, open the spare cold shock air channel or lower the cold shock air temperature setting value;

[0033] If the predicted temperature And there is a downward trend, generating a control instruction to reduce the cold shock air flow rate, and the opening change is also calculated according to the proportional control strategy, but in the opposite direction.

[0034] Furthermore, the cold shock gas uses a multi-component gas composed of methanol and inert gas, and the intelligent control unit controls the proportion of methanol and inert gas components according to different reaction stages and temperature requirements.

[0035] Furthermore, the cold shock gas pipeline adopts a graded and layered cooling structure, the cold shock gas is divided into multiple paths and injected into different beds and regions of the reactor respectively, and the cold shock gas volume and temperature are allocated according to the temperature distribution of each layer and the reaction heat generation rate.

[0036] Furthermore, the heat exchanger unit and surrounding energy-consuming equipment form an energy recovery and recycling network, and the intelligent control unit controls the heat distribution path.

[0037] Furthermore, an environmentally friendly cold shock medium is used to replace part of the cold shock gas, and the cold shock medium includes carbon dioxide supercritical fluid and water-based nanofluid.

[0038] A cold shock cooling method for a fixed bed reactor comprises the following steps:

[0039] S1, using the temperature sensor array unit to monitor the temperature of the first section, the second section and other beds of the reactor in real time, and transmit the data to the intelligent control unit;

[0040] S2. The intelligent control unit starts the pre-regulation program according to the preset temperature threshold and the dynamic change model when the outlet temperature of the first bed reaches 350°C, and adjusts the opening of the methanol steam cold shock gas regulating valve TV-260505 at the inlet of the second bed in the range of 350-370°C, so that the inlet temperature of the second bed is stabilized at 310°C and the outlet temperature is maintained at 360°C. At the same time, the temperature of each point in the reactor is controlled to be lower than 370°C and not exceed 400°C.

[0041] S3, the intelligent control unit uses a preset algorithm to adjust the control strategy according to the reactor operating conditions and bed temperature change trends, predict temperature changes in advance and adjust the cold shock gas parameters;

[0042] S4, comprehensively monitoring the flow rate, pressure, methanol concentration of the cold shock gas, the pressure in the reactor, the concentration of reactants and other parameters, and the intelligent control unit establishes a multivariate correlation model and optimizes the cold shock gas regulation strategy accordingly;

[0043] S5, using a multi-component cold shock gas system consisting of methanol and inert gas, according to different reaction stages and temperature requirements, the intelligent control unit accurately adjusts the proportion of each component to perform cooling operations;

[0044] S6. The cold shock gas is divided into multiple paths and injected into different beds and regions of the reactor through a graded and layered cooling structure, and the amount and temperature of the cold shock gas are allocated according to the temperature distribution of each layer and the reaction heat generation rate;

[0045] S7, using the heat exchanger unit to recover the waste heat of the cold shock air and forming an energy recovery and recycling network with the surrounding energy-consuming equipment, and the intelligent control unit controls the heat distribution path to achieve energy reuse;

[0046] S8. Under certain working conditions, use environmentally friendly cold shock medium to replace part of the cold shock gas for cooling operations.

[0047] Compared with the known prior art, the technical solution provided by the present invention has the following beneficial effects:

[0048] (1) With the help of the temperature sensor array distributed in each bed layer, the present invention can obtain the temperature data in the reactor in real time, comprehensively and accurately, providing a reliable basis for subsequent precise control. The intelligent control unit uses an advanced preset algorithm to select a suitable ARIMA model or LSTM model for temperature prediction under different working conditions, and combines it with a proportional control strategy to respond to temperature changes in advance and accurately adjust the cold shock gas flow rate and component ratio. This effectively avoids the lag of traditional control methods, controls the temperature fluctuation in the reactor within a very small range, ensures that the reaction is always in the optimal temperature conditions, and significantly improves the reaction efficiency and the stability of product quality.

[0049] Strict temperature threshold control effectively prevents catalyst deactivation and temperature runaway caused by excessive temperature, extends catalyst service life, reduces production losses caused by reactor failure and shutdown, and improves production continuity and stability.

[0050] (2) A multi-component cold shock gas system consisting of methanol and inert gas is used, and its component ratio is precisely controlled according to different reaction stages and temperature requirements, giving full play to the heat absorption characteristics of methanol and the regulating effect of inert gas. In the early stage of the reaction, the methanol ratio is appropriately increased to quickly absorb the reaction heat; in the later stage of the reaction, the inert gas ratio is adjusted according to the catalyst activity maintenance requirements, while ensuring the cooling effect, the waste of cold shock gas is minimized, the utilization efficiency of cold shock gas is improved, and the production cost is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0052] Figure 1 It is a structural schematic diagram of the present invention;

[0053] Figure 2 The present invention is a flow chart of the method. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0055] The present invention will be further described below in conjunction with the embodiments.

[0056] Example 1: Figure 1 As shown, a cold shock cooling system for a fixed bed reactor is characterized by comprising:

[0057] A temperature sensor array unit, used for collecting temperature data in real time;

[0058] An intelligent control unit, used for receiving temperature data and issuing control instructions to the flow regulating valve group unit and the heat exchanger unit based on a preset algorithm;

[0059] The preset algorithm steps include data acquisition and preprocessing, feature extraction and operating condition identification, temperature prediction model prediction, control strategy generation and command output, and adjust the control strategy according to the reactor operating conditions and bed temperature change trends to predict temperature changes;

[0060] Data collection and preprocessing include collecting temperature data of each bed layer of the reactor, cold shock gas flow rate, pressure, methanol concentration, pressure in the reactor, and reactant concentration, and filtering the temperature data; feature extraction and operating condition identification are to calculate the temperature change rate, cold shock gas flow rate change rate, and pressure change rate in the reactor to form a feature vector, and identify the reactor operating condition through the support vector machine model; the temperature prediction model predicts the temperature by selecting the ARIMA model or LSTM model according to the operating condition; the control strategy generation and command output are based on the comparison of the predicted temperature with the preset temperature threshold, and the cold shock gas flow rate, component ratio, and the start of cooling measures;

[0061] The flow regulating valve group unit is used to control the flow and direction of the cold shock gas according to the instructions of the intelligent control unit;

[0062] The heat exchanger unit is used to recover the waste heat of the cold shock air for heat reuse.

[0063] Furthermore, the preset algorithm of the intelligent control unit adjusts the control strategy according to the reactor operating conditions and the trend of bed temperature changes, predicts temperature changes and generates control instructions.

[0064] Furthermore, the preset algorithm steps of the intelligent control unit include:

[0065] Data acquisition and preprocessing: Obtain temperature data of the first and second sections of the reactor and other beds from temperature sensors ,... , where t represents time, n represents the number of beds, and the cold shock gas flow rate is collected at the same time ,pressure , methanol concentration and the pressure inside the reactor , reactant concentration ;

[0066] Temperature data For filtering, the formula is:

[0067]

[0068] in, is the temperature data after filtering, m is the moving average window width;

[0069] Feature extraction and working condition identification: Calculate the temperature change rate based on the processed temperature data , the formula is:

[0070]

[0071] in, is the time interval, and the cold shock air flow rate change rate is calculated at the same time , pressure change rate in the reactor , the temperature change rate , cold shock air flow rate change rate , pressure change rate in the reactor ,pressure , methanol concentration and the pressure inside the reactor , reactant concentration Composition of feature vectors: ;

[0072] The characteristic vector is identified through the working condition classification model to judge the current reactor working condition. The reactor working condition includes stable working condition and fluctuating working condition. The working condition classification model adopts the support vector machine model, and the decision function is:

[0073]

[0074] Where w is the weight vector and b is the bias. When , it is determined to be a fluctuating condition; when When , it is judged as a stable working condition;

[0075] Temperature prediction model prediction: Different temperature prediction models are selected according to the working condition identification results. If it is in a stable working condition, the ARIMA model based on time series is used for temperature prediction; if it is in a fluctuating working condition, the prediction model based on long short-term memory network is used;

[0076] For the ARIMA model, the temperature time series is differentiated, and the differentiated series is assumed to be , the parameters of the ARIMA model are determined by the least squares method, including the autoregressive order p, the difference order d, the moving average order q and the model coefficient, and the model is used to predict the temperature value in the future , where k is the prediction step length, and the prediction formula is:

[0077]

[0078] in, and are the autoregressive and moving average coefficients, respectively. is a white noise sequence, is a constant;

[0079] For the LSTM model, historical temperature data and other related parameters are used as input sequences, and the future temperature forecast value is obtained through forward propagation calculation of the model. ,The training process of the LSTM model adjusts the network weights through the back-propagation algorithm to minimize the prediction error;

[0080] Control strategy generation and command output: Based on the predicted temperature value With preset temperature threshold , , For comparison, if the predicted temperature And there is an upward trend, generating a control command to increase the cold shock air flow, the control command is achieved by adjusting the opening of the flow control valve, the opening change Deviation from predicted temperature Proportional control strategy can be adopted, the formula is:

[0081]

[0082] in, is the proportionality coefficient. At the same time, according to the current methanol concentration According to the temperature changes, adjust the ratio of methanol to inert gas in the cold shock gas. If the temperature rises quickly and the methanol concentration is low, increase the methanol ratio; if the temperature rises slowly and the methanol concentration is high, increase the inert gas ratio;

[0083] If the predicted temperature In addition to increasing the cold shock air flow rate, start cooling measures, open the spare cold shock air channel or lower the cold shock air temperature setting value;

[0084] If the predicted temperature And there is a downward trend, generating a control instruction to reduce the cold shock air flow rate, and the opening change is also calculated according to the proportional control strategy, but in the opposite direction.

[0085] Furthermore, the cold shock gas uses a multi-component gas composed of methanol and inert gas, and the intelligent control unit controls the proportion of methanol and inert gas components according to different reaction stages and temperature requirements.

[0086] Furthermore, the cold shock gas pipeline adopts a graded and layered cooling structure, which divides the cold shock gas into multiple paths and injects them into different beds and areas of the reactor respectively, and distributes the cold shock gas volume and temperature according to the temperature distribution of each layer and the reaction heat generation rate.

[0087] Furthermore, the heat exchanger unit and surrounding energy-consuming equipment form an energy recovery and recycling network, and the intelligent control unit controls the heat distribution path.

[0088] Furthermore, an environmentally friendly cold shock medium is used to replace part of the cold shock gas, and the cold shock medium includes carbon dioxide supercritical fluid and water-based nanofluid.

[0089] In a specific embodiment, a fixed-bed methanol-to-olefins reactor with a processing capacity of 100 tons / day is selected to install the cold shock cooling system of the present invention. The temperature sensor array unit adopts high-precision platinum resistance temperature sensors, which are evenly distributed on the two beds of the reactor to ensure that the temperature of each key part can be accurately measured. The intelligent control unit adopts an industrial-grade controller with powerful data processing capabilities and fast response speed. The flow control valve group unit uses an electric control valve to achieve a flow control range of 0-100%, and the heat exchanger unit adopts a plate heat exchanger unit with a heat exchange efficiency of more than 90%.

[0090] The reaction raw material is methanol with a purity of 99.5%, the reaction pressure is 0.8MPa, the reaction temperature is initially set at around 300°C, the cold shock gas uses a multi-gas composed of methanol and nitrogen, and the initial methanol ratio is set to 50%.

[0091] At the beginning of the reaction, the temperature sensor collects the temperature data of each bed layer in real time and transmits it to the intelligent control unit. As the reaction proceeds, when the outlet temperature of the first bed layer reaches 350°C, the intelligent control unit quickly starts the pre-adjustment program, calculates the opening adjustment of the TV-260505 regulating valve according to the preset algorithm, and appropriately increases the opening of the methanol steam cold shock gas regulating valve TV-260505 at the inlet of the second bed layer, so that the inlet temperature of the second bed layer is stabilized at 310°C. At the same time, the intelligent control unit continuously monitors other parameters, such as cold shock gas flow, pressure, methanol concentration, pressure in the reactor, and reactant concentration.

[0092] During the reaction process, when the raw material flow rate fluctuates, such as when the methanol feed rate fluctuates by ±10% within 1 hour, the intelligent control unit determines that the reactor is in a fluctuating condition through feature extraction and operating condition identification, and immediately switches to the LSTM temperature prediction model. According to the prediction results, the cold shock gas flow rate and the ratio of methanol to nitrogen are adjusted in time. For example, when the temperature has an upward trend and the methanol concentration is low, the methanol ratio is increased to 60%, and the cold shock gas flow rate is increased by 20%, which effectively suppresses the rapid rise in temperature and ensures that the temperature at each point in the reactor is always below 370°C and does not exceed 400°C.

[0093] After a long period of operation, the heat exchanger unit was used to recover the waste heat of the cold shock gas, which increased the temperature of the raw methanol by 35°C before entering the reactor, significantly reducing the energy consumption during the reaction. At the same time, through the graded and layered cooling structure, the uniformity of the temperature distribution of each bed layer was improved by 20%, the selectivity of the products ethylene and propylene was increased by 8% and 12% respectively, and the reaction yield was increased by 10%, achieving good economic benefits and product quality improvement effects.

[0094] In another specific embodiment, for a fixed-bed styrene synthesis reactor with a capacity of 50 cubic meters, the cold shock cooling system of the present invention is installed, the temperature sensor is a thermocouple sensor, which is arranged in the four bed layers of the reactor, the intelligent control unit adopts a programmable logic controller (PLC), and the control algorithm is implemented in combination with the control software, the flow control valve group unit adopts a pneumatic control valve, which has the characteristics of fast response speed and good sealing, and the heat exchanger unit adopts a shell and tube heat exchanger unit, which can adapt to higher pressure and temperature conditions.

[0095] The reaction raw materials are ethylbenzene and an appropriate amount of catalyst, the reaction temperature is controlled between 320-380°C, the reaction pressure is 1.2MPa, and the cold shock gas uses a multi-component gas composed of methanol and argon, with an initial methanol ratio of 40%.

[0096] After the reaction starts, the temperature sensor transmits the temperature data of each bed layer to the intelligent control unit. When the temperature of the first bed layer approaches 350°C, the intelligent control unit adjusts the opening of the cold shock gas regulating valve according to the preset program to stabilize the inlet temperature of the second bed layer at around 310°C. In the middle of the reaction, as the reaction heat increases, the intelligent control unit dynamically adjusts the ratio of methanol and argon in the cold shock gas according to the temperature change and operating condition identification results. For example, when the temperature rises rapidly and the methanol concentration is relatively low, the methanol ratio is increased to 50%, and the cold shock gas flow rate is increased to ensure that the reactor temperature is stable within the set range.

[0097] When the reactor has a local overtemperature, the intelligent control unit quickly increases the amount of cooling gas in the area and appropriately reduces the cooling gas temperature through a graded and layered cooling structure, so that the temperature of the local high-temperature area is reduced by 20°C within 5 minutes, effectively preventing catalyst deactivation and intensification of side reactions.

[0098] After continuous operation, the heat recovered by the heat exchanger unit is used to preheat the ethylbenzene raw material, which increases the ethylbenzene preheating temperature by 40°C and the energy utilization efficiency by 35%. At the same time, the purity of the product styrene is increased from the original 98% to 99.2%, and the yield is increased by 12%, fully demonstrating the significant advantages of the present invention in the styrene synthesis reaction.

[0099] Example 2: Figure 2 As shown, a cold shock cooling method for a fixed bed reactor comprises the following steps:

[0100] S1, using the temperature sensor array unit to monitor the temperature of the first section, the second section and other beds of the reactor in real time, and transmit the data to the intelligent control unit;

[0101] S2. The intelligent control unit starts the pre-regulation program according to the preset temperature threshold and the dynamic change model when the outlet temperature of the first bed reaches 350°C, and adjusts the opening of the methanol steam cold shock gas regulating valve TV-260505 at the inlet of the second bed in the range of 350-370°C, so that the inlet temperature of the second bed is stabilized at 310°C and the outlet temperature is maintained at 360°C. At the same time, the temperature of each point in the reactor is controlled to be lower than 370°C and not exceed 400°C.

[0102] S3, the intelligent control unit uses a preset algorithm to adjust the control strategy according to the reactor operating conditions and bed temperature change trends, predict temperature changes in advance and adjust the cold shock gas parameters;

[0103] S4, comprehensively monitoring the flow rate, pressure, methanol concentration of the cold shock gas, the pressure in the reactor, the concentration of reactants and other parameters, and the intelligent control unit establishes a multivariate correlation model and optimizes the cold shock gas regulation strategy accordingly;

[0104] S5, using a multi-component cold shock gas system consisting of methanol and inert gas, according to different reaction stages and temperature requirements, the intelligent control unit accurately adjusts the proportion of each component to perform cooling operations;

[0105] S6. The cold shock gas is divided into multiple paths and injected into different beds and regions of the reactor through a graded and layered cooling structure, and the amount and temperature of the cold shock gas are allocated according to the temperature distribution of each layer and the reaction heat generation rate;

[0106] S7, using the heat exchanger unit to recover the waste heat of the cold shock air and forming an energy recovery and recycling network with the surrounding energy-consuming equipment, and the intelligent control unit controls the heat distribution path to achieve energy reuse;

[0107] S8. Under certain working conditions, use environmentally friendly cold shock medium to replace part of the cold shock gas for cooling operations.

[0108] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. A cold shock cooling system for a fixed bed reactor, characterized in that: include: A temperature sensor array unit, used for collecting temperature data in real time; An intelligent control unit, used for receiving temperature data and issuing control instructions to the flow regulating valve group unit and the heat exchanger unit based on a preset algorithm; The preset algorithm steps include data acquisition and preprocessing, feature extraction and operating condition identification, temperature prediction model prediction, control strategy generation and instruction output, and adjusting the control strategy according to the reactor operating conditions and bed temperature change trends to predict temperature changes; Data collection and preprocessing include collecting temperature data of each bed layer of the reactor, cold shock gas flow rate, pressure, methanol concentration, pressure in the reactor, and reactant concentration, and filtering the temperature data; feature extraction and operating condition identification are to calculate the temperature change rate, cold shock gas flow rate change rate, and pressure change rate in the reactor to form a feature vector, and identify the reactor operating condition through the support vector machine model; the temperature prediction model predicts the temperature by selecting the ARIMA model or LSTM model according to the operating condition; the control strategy generation and command output are based on the comparison of the predicted temperature with the preset temperature threshold, and the cold shock gas flow rate, component ratio, and the start of cooling measures; The flow regulating valve group unit is used to control the flow and direction of the cold shock gas according to the instructions of the intelligent control unit; The heat exchanger unit is used to recover the waste heat of the cold shock air for heat reuse.

2. The cold shock cooling system for a fixed bed reactor according to claim 1, characterized in that: The preset algorithm of the intelligent control unit adjusts the control strategy according to the reactor operating conditions and the bed temperature change trend, predicts the temperature change and generates control instructions.

3. The cold shock cooling system for a fixed bed reactor according to claim 1, characterized in that: The preset algorithm steps of the intelligent control unit include: Data acquisition and preprocessing: Obtain temperature data of the first and second sections of the reactor and other beds from temperature sensors ,... , where t represents time, n represents the number of beds, and the cold shock gas flow rate is collected at the same time ,pressure , methanol concentration and the pressure inside the reactor , reactant concentration ; Temperature data For filtering, the formula is: in, is the temperature data after filtering, m is the moving average window width; Feature extraction and working condition identification: Calculate the temperature change rate based on the processed temperature data , the formula is: in, is the time interval, and the cold shock air flow rate change rate is calculated at the same time , pressure change rate in the reactor , the temperature change rate , cold shock air flow rate change rate , pressure change rate in the reactor ,pressure , methanol concentration and the pressure inside the reactor , reactant concentration Composition of feature vectors: ; The characteristic vector is identified through the working condition classification model to judge the current reactor working condition. The reactor working condition includes stable working condition and fluctuating working condition. The working condition classification model adopts the support vector machine model, and the decision function is: Where w is the weight vector and b is the bias. When , it is determined to be a fluctuating condition; when When , it is judged as a stable working condition; Temperature prediction model prediction: Different temperature prediction models are selected according to the working condition identification results. If it is in a stable working condition, the ARIMA model based on time series is used for temperature prediction; if it is in a fluctuating working condition, the prediction model based on long short-term memory network is used; For the ARIMA model, the temperature time series is differentiated, and the differentiated series is assumed to be , the parameters of the ARIMA model are determined by the least squares method, including the autoregressive order p, the difference order d, the moving average order q and the model coefficient, and the model is used to predict the temperature value in the future , where k is the prediction step length, and the prediction formula is: in, and are the autoregressive and moving average coefficients, respectively. is a white noise sequence, is a constant; For the LSTM model, historical temperature data and other related parameters are used as input sequences, and the future temperature forecast value is obtained through forward propagation calculation of the model. ,The training process of the LSTM model adjusts the network weights through the back-propagation algorithm to minimize the prediction error; Control strategy generation and command output: Based on the predicted temperature value With preset temperature threshold , , For comparison, if the predicted temperature And there is an upward trend, generating a control command to increase the cold shock air flow, the control command is achieved by adjusting the opening of the flow control valve, the opening change Deviation from predicted temperature Proportional control strategy can be adopted, the formula is: in, is the proportionality coefficient. At the same time, according to the current methanol concentration According to the temperature changes, adjust the ratio of methanol to inert gas in the cold shock gas. If the temperature rises quickly and the methanol concentration is low, increase the methanol ratio; if the temperature rises slowly and the methanol concentration is high, increase the inert gas ratio; If the predicted temperature In addition to increasing the cold shock air flow rate, start cooling measures, open the spare cold shock air channel or lower the cold shock air temperature setting value; If the predicted temperature And there is a downward trend, generating a control instruction to reduce the cold shock air flow rate, and the opening change is also calculated according to the proportional control strategy, but in the opposite direction.

4. The cold shock cooling system for a fixed bed reactor according to claim 1, characterized in that: The cold shock gas adopts a multi-component gas composed of methanol and inert gas, and the intelligent control unit controls the proportion of methanol and inert gas components according to different reaction stages and temperature requirements.

5. The cold shock cooling system for a fixed bed reactor according to claim 1, characterized in that: The cold shock gas pipeline adopts a graded and layered cooling structure, divides the cold shock gas into multiple paths and injects them into different beds and areas of the reactor respectively, and distributes the cold shock gas volume and temperature according to the temperature distribution of each layer and the reaction heat generation rate.

6. The cold shock cooling system for a fixed bed reactor according to claim 1, characterized in that: The heat exchanger unit and surrounding energy-consuming equipment form an energy recovery and recycling network, and the intelligent control unit controls the heat distribution path.

7. The cold shock cooling system for a fixed bed reactor according to claim 1, characterized in that: An environmentally friendly cold shock medium is used to replace part of the cold shock gas, wherein the cold shock medium includes carbon dioxide supercritical fluid and water-based nanofluid.

8. A cold shock cooling method for a fixed bed reactor, characterized in that: The following steps are involved: S1, using the temperature sensor array unit to monitor the temperature of the first section, the second section and other beds of the reactor in real time, and transmit the data to the intelligent control unit; S2. The intelligent control unit starts the pre-regulation program according to the preset temperature threshold and the dynamic change model when the outlet temperature of the first bed reaches 350°C, and adjusts the opening of the methanol steam cold shock gas regulating valve TV-260505 at the inlet of the second bed in the range of 350-370°C, so that the inlet temperature of the second bed is stabilized at 310°C and the outlet temperature is maintained at 360°C. At the same time, the temperature of each point in the reactor is controlled to be lower than 370°C and not exceed 400°C. S3, the intelligent control unit uses a preset algorithm to adjust the control strategy according to the reactor operating conditions and bed temperature change trends, predict temperature changes in advance and adjust the cold shock gas parameters; S4, comprehensively monitoring the flow rate, pressure, methanol concentration of the cold shock gas, the pressure in the reactor, the concentration of reactants and other parameters, and the intelligent control unit establishes a multivariate correlation model and optimizes the cold shock gas regulation strategy accordingly; S5, using a multi-component cold shock gas system consisting of methanol and inert gas, according to different reaction stages and temperature requirements, the intelligent control unit accurately adjusts the proportion of each component to perform cooling operations; S6. The cold shock gas is divided into multiple paths and injected into different beds and regions of the reactor through a graded and layered cooling structure, and the amount and temperature of the cold shock gas are allocated according to the temperature distribution of each layer and the reaction heat generation rate; S7, using the heat exchanger unit to recover the waste heat of the cold shock air and forming an energy recovery and recycling network with the surrounding energy-consuming equipment, and the intelligent control unit controls the heat distribution path to achieve energy reuse; S8. Under certain working conditions, use environmentally friendly cold shock medium to replace part of the cold shock gas for cooling operations.

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